Currently, Internet access is important for email, information search and E-commerce. To provide Internet access for a user, one ISP account, one phone line, one modem, and a personal computer are needed. However, in a simultaneous multi-user system, such as a local area network (LAN) built in an office, it will spend a considerable cost to provide ISP accounts and phone lines for all of the computers. To solve this problem, program products for multi-users to share one modem and single active phone line are developed. The conventional multi-user/single modem system 1 is illustrated in FIG. 1. There is a plurality of computers 11, 12, . . . , 15, etc., connected by a local area network (LAN) 10. There is only one computer, i.e. the computer 12, which provides Internet access. The computer 12 is connected with a modem 121 and a telephone terminal 122, and is called a "server". There is only one server 12 in the multi-user system 1. The server itself, with no problem, can connect to the Internet with a telephone and an ISP account. Other computers in the network, equipped with no modem, cannot connect to the Internet directly. Instead, data for Internet access are transmitted to the server 12 through LAN 10. The server 12 converts the private unregistered IP address into the global registered IP address by a network address translator (NAT) technique. The registered IP address is then transmitted to the Internet. Data responded by the Internet is transmitted to the server 12 and the server 12 will identify and send data received from Internet to the right computer of the system 1.
Since the conventional system 1 has only one fixed server 12, many problems will happen. If the server 12 is invalid because of being turned off or other reason, all the user of the system 1 will not be able to connect to the Internet. Accordingly, the server 12 must be kept on turned and operated continuously. Such a situation will be inconvenient for the user and the life of the server 12 will be shortened. Additionally, to keep the power turned on continuously is wasteful. It is then attempted by the present invention to solve the above-mentioned problems.